Ali B Lubis, Anna J Bailey, Marko Hanževački, Christopher Williams, Mehul Jesani, Lola González-Sánchez, Christopher J Arthur, Hannah C Wilson, Andrea E Gallio, Peter C E Moody, Matthew P Crump, Adrian J Mulholland, Allen M Orville, Jonathan Clayden, Emma L Raven
Indoleamine 2,3-dioxygenase (IDO) is a heme-dependent enzyme that catalyzes the first, rate-limiting step of the kynurenine pathway─the oxidation of l-tryptophan to N-formylkynurenine (NFK). IDO-catalyzed depletion of tryptophan levels and accumulation of kynurenine pathway metabolites is an important control mechanism of the immune responses in cells. IDO has been considered as a dioxygenase because two atoms of oxygen are inserted into the substrate. Here, we use LC-MS and NMR to examine the reactivity of human IDO (hIDO) with l-tryptophan (l-Trp) and several other tryptophan analogues. Alongside dioxygenase activity, we identify a concurrent pathway of heme-dependent monooxygenase activity in the reaction of hIDO with l-Trp, leading to the formation of a cyclic 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid (HPIC) species. Reaction profiles for the reaction of hIDO with other tryptophan analogues are likewise examined. Formation of HPIC from l-Trp is reproduced in HeLa cells induced to overexpress hIDO, indicating that this dual dioxygenase/monooxygenase reactivity also occurs biologically. Notably, the reaction of hIDO with β-[3-benzo(b)thienyl]-l-alanine (S-l-Trp)─a known inhibitor ─yielded only the cyclic HPIC analogue, suggesting that IDO activity can be selectively directed toward the monooxygenase pathway. Molecular dynamics simulations underscore the critical role of substrate plasticity within the active site of hIDO, while DFT calculations provide a mechanistic rationalization for the observed product distributions. Together, the data demonstrate dual dioxygenase/monooxygenase functionality for human IDO. As the overall gatekeeper for control of tryptophan levels in cells, the findings provide mechanistic information on relevance to therapeutic strategies focused on IDO inhibition.
{"title":"Monooxygenase Activity of Indoleamine 2,3-Dioxygenase.","authors":"Ali B Lubis, Anna J Bailey, Marko Hanževački, Christopher Williams, Mehul Jesani, Lola González-Sánchez, Christopher J Arthur, Hannah C Wilson, Andrea E Gallio, Peter C E Moody, Matthew P Crump, Adrian J Mulholland, Allen M Orville, Jonathan Clayden, Emma L Raven","doi":"10.1021/jacs.5c17552","DOIUrl":"10.1021/jacs.5c17552","url":null,"abstract":"<p><p>Indoleamine 2,3-dioxygenase (IDO) is a heme-dependent enzyme that catalyzes the first, rate-limiting step of the kynurenine pathway─the oxidation of l-tryptophan to <i>N</i>-formylkynurenine (NFK). IDO-catalyzed depletion of tryptophan levels and accumulation of kynurenine pathway metabolites is an important control mechanism of the immune responses in cells. IDO has been considered as a dioxygenase because two atoms of oxygen are inserted into the substrate. Here, we use LC-MS and NMR to examine the reactivity of human IDO (hIDO) with l-tryptophan (l-Trp) and several other tryptophan analogues. Alongside dioxygenase activity, we identify a concurrent pathway of heme-dependent monooxygenase activity in the reaction of hIDO with l-Trp, leading to the formation of a cyclic 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-<i>b</i>]indole-2-carboxylic acid (HPIC) species. Reaction profiles for the reaction of hIDO with other tryptophan analogues are likewise examined. Formation of HPIC from l-Trp is reproduced in HeLa cells induced to overexpress hIDO, indicating that this dual dioxygenase/monooxygenase reactivity also occurs biologically. Notably, the reaction of hIDO with β-[3-benzo(b)thienyl]-l-alanine (S-l-Trp)─a known inhibitor ─yielded only the cyclic HPIC analogue, suggesting that IDO activity can be selectively directed toward the monooxygenase pathway. Molecular dynamics simulations underscore the critical role of substrate plasticity within the active site of hIDO, while DFT calculations provide a mechanistic rationalization for the observed product distributions. Together, the data demonstrate dual dioxygenase/monooxygenase functionality for human IDO. As the overall gatekeeper for control of tryptophan levels in cells, the findings provide mechanistic information on relevance to therapeutic strategies focused on IDO inhibition.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":" ","pages":""},"PeriodicalIF":15.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146117140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Precise control of chemo- and regioselectivity in intermolecular difunctionalization of alkenes remains a long-standing challenge in organic synthesis. Here, we report a heterogeneous cobalt single-atom-site catalyst that enables selective 1,2-sulfonamidoazidation of styrenes. The system features good functional group tolerance and excellent recyclability. By leveraging the characteristics of single-atom-site catalysis, this work provides a valuable platform for achieving highly selective, efficient, and sustainable styrene functionalization.
{"title":"Chemoselective 1,2-Sulfonamidoazidation of Styrene via Single-Atom-Site Cobalt Catalysis.","authors":"Wenxuan Xue, Jing Jia, Mingtao Wu, Li-Ming Yang, Rajenahally V Jagadeesh, Matthias Beller, Conghui Tang","doi":"10.1021/jacs.5c12264","DOIUrl":"https://doi.org/10.1021/jacs.5c12264","url":null,"abstract":"<p><p>Precise control of chemo- and regioselectivity in intermolecular difunctionalization of alkenes remains a long-standing challenge in organic synthesis. Here, we report a heterogeneous cobalt single-atom-site catalyst that enables selective 1,2-sulfonamidoazidation of styrenes. The system features good functional group tolerance and excellent recyclability. By leveraging the characteristics of single-atom-site catalysis, this work provides a valuable platform for achieving highly selective, efficient, and sustainable styrene functionalization.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":" ","pages":""},"PeriodicalIF":15.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146117049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ce Liu, Zhaojie Wang, Xiaoqing Lu, Shoufu Cao, Yang-Gang Wang
Bulk gold, renowned for its catalytic inertness, can be transformed into an exceptionally active catalyst by engineering undercoordinated sites on its surface. However, directly sculpting such active sites from extended terraces remains a fundamental challenge. Here, we demonstrate a programmable strategy to dynamically generate subnanometer Au clusters directly from inert Au(111) surfaces, unlocking superior activity for CO oxidation. By integrating large-scale machine learning molecular dynamics with density functional theory, we decode the atomistic pathway of this restructuring process. Our approach employs thermal-CO pressure cycles to induce the ejection of step-edge atoms, forming mobile Au–CO complexes. Subsequent cooling kinetically traps these complexes into metastable, subnanometer clusters (3–6 atoms). A controlled reduction of CO exposure then precisely exposes the catalytically crucial undercoordinated sites while maintaining cluster stability. Crucially, these sculpted clusters exhibit a CO oxidation activity that far exceeds that of pristine step edges, terraces, or conventional single-atom sites. This work establishes reaction condition engineering as a powerful paradigm for sculpting active catalysts directly from bulk materials by bypassing traditional synthetic routes.
{"title":"Sculpting Superior Subnanometer Catalysts Directly from Inert Gold","authors":"Ce Liu, Zhaojie Wang, Xiaoqing Lu, Shoufu Cao, Yang-Gang Wang","doi":"10.1021/jacs.5c22389","DOIUrl":"https://doi.org/10.1021/jacs.5c22389","url":null,"abstract":"Bulk gold, renowned for its catalytic inertness, can be transformed into an exceptionally active catalyst by engineering undercoordinated sites on its surface. However, directly sculpting such active sites from extended terraces remains a fundamental challenge. Here, we demonstrate a programmable strategy to dynamically generate subnanometer Au clusters directly from inert Au(111) surfaces, unlocking superior activity for CO oxidation. By integrating large-scale machine learning molecular dynamics with density functional theory, we decode the atomistic pathway of this restructuring process. Our approach employs thermal-CO pressure cycles to induce the ejection of step-edge atoms, forming mobile Au–CO complexes. Subsequent cooling kinetically traps these complexes into metastable, subnanometer clusters (3–6 atoms). A controlled reduction of CO exposure then precisely exposes the catalytically crucial undercoordinated sites while maintaining cluster stability. Crucially, these sculpted clusters exhibit a CO oxidation activity that far exceeds that of pristine step edges, terraces, or conventional single-atom sites. This work establishes reaction condition engineering as a powerful paradigm for sculpting active catalysts directly from bulk materials by bypassing traditional synthetic routes.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"89 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lu-Yi Chen, Wei-Lin Lu, Tanvi Pathania, I-Hsuan Chu, Meng-Ru Ho, Wei-Chen Chuang, Yuan-Chao Lou, Ta I. Hung, Yohei Miyanoiri, Chia-en A. Chang, Kuen-Phon Wu
AI-designed protein variants have demonstrated remarkable resistance to heat and chemical stress, yet the molecular mechanisms underlying this stability remain unclear. Here, we present a comprehensive biophysical and nuclear magnetic resonance (NMR) analysis of thermally stable ubiquitin and its ProteinMPNN-designed variants, R4 and R10, together with a second system based on the less stable ISG15 C-terminal domain (ISG15-CTD). Both R4/R10 and ProteinMPNN-designed ISG15-CTD variants (ICVs) exhibit extraordinary thermostability beyond 120 °C, and resist extreme denaturation at pH 3.0 in 8 M urea. NMR relaxation and hydrogen–deuterium exchange, and molecular-dynamics simulations reveal a protective mesostructured hydration shell that strengthens the hydrogen bonding network between protein-bound and bulk water, thereby suppressing unfolding. Sequence and electrostatic analyses indicate that this hydration arises from charge enrichment and clustering on the protein surface. These findings identify mesostructured hydration as a general, sequence-encoded mechanism of ProteinMPNN-driven stability and provide a physical framework for designing highly resilient biomolecules.
{"title":"Mesostructured Water Enhances Stability of ProteinMPNN-Designed Ubiquitin-Fold Proteins","authors":"Lu-Yi Chen, Wei-Lin Lu, Tanvi Pathania, I-Hsuan Chu, Meng-Ru Ho, Wei-Chen Chuang, Yuan-Chao Lou, Ta I. Hung, Yohei Miyanoiri, Chia-en A. Chang, Kuen-Phon Wu","doi":"10.1021/jacs.5c19875","DOIUrl":"https://doi.org/10.1021/jacs.5c19875","url":null,"abstract":"AI-designed protein variants have demonstrated remarkable resistance to heat and chemical stress, yet the molecular mechanisms underlying this stability remain unclear. Here, we present a comprehensive biophysical and nuclear magnetic resonance (NMR) analysis of thermally stable ubiquitin and its ProteinMPNN-designed variants, R4 and R10, together with a second system based on the less stable ISG15 C-terminal domain (ISG15-CTD). Both R4/R10 and ProteinMPNN-designed ISG15-CTD variants (ICVs) exhibit extraordinary thermostability beyond 120 °C, and resist extreme denaturation at pH 3.0 in 8 M urea. NMR relaxation and hydrogen–deuterium exchange, and molecular-dynamics simulations reveal a protective mesostructured hydration shell that strengthens the hydrogen bonding network between protein-bound and bulk water, thereby suppressing unfolding. Sequence and electrostatic analyses indicate that this hydration arises from charge enrichment and clustering on the protein surface. These findings identify mesostructured hydration as a general, sequence-encoded mechanism of ProteinMPNN-driven stability and provide a physical framework for designing highly resilient biomolecules.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"29 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaofeng Wu, Fan Xing, Yang Yang, Xiaoyang Liu, Gyoungmi Kim, Qiaochu Jiang, Ying Xu, Jing-Jing Hu, Gaolin Liang, Juyoung Yoon
Photoimmunotherapy has been a promising method for eradicating malignant tumors, but remains largely limited by tumor hypoxia and off-target adverse effects. To address these limitations, we develop hypoxia-tolerant small ligand-caged photosensitizer (PS) P1/P2 that are delivered to tumor based on an albumin-hijacking strategy by exploiting endogenous serum albumin as a tumor-localized carrier, achieving exceptional tumor accumulation and overcoming tumor hypoxia to realize the combined photoimmunotherapy. Albumin can trigger the acetyl group of P1/P2, initiating a 1,6-rearrangement elimination cascade to release a quinone methide intermediate captured by albumin to form a stable adduct via site-specific 1,6-Michael addition, as verified by in vitro experiments, including high performance liquid chromatography, mass spectra, spectroscopic spectra, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses but control probes P3/P4 fail. In vivo imaging revealed that P1/P2 displayed more enhanced tumor accumulation post injection than P3/P4 did in 4T1-bearing mouse models and P1 further enabled broad-spectrum efficacy across several tumor models. Moreover, by light-irradiation-generating superoxide anions and hydroxyl radicals, P1-mediated photodynamic therapy achieves tumor-inhibiting action with approximately 92% regression in a breast mouse model and triggers immunogenic cell death induction, synergizing with programmed death-ligand 1 therapy to further activate systemic antitumor immunity and suppress both primary and distant tumors with approximately 95% tumor growth inhibition. Crucially, this platform may extend its applicability to diverse payloads such as imaging agents, therapeutics, and immunomodulators by replacing the PS warhead and advance delivery methods for clinical imaging and therapy.
{"title":"Caged Ligand-Decorated Near-Infrared Photosensitizer with In Vivo Albumin-Hijacking Capacity for Tumor-Targeted Hypoxia-Tolerant Photoimmunotherapy of Cancer","authors":"Xiaofeng Wu, Fan Xing, Yang Yang, Xiaoyang Liu, Gyoungmi Kim, Qiaochu Jiang, Ying Xu, Jing-Jing Hu, Gaolin Liang, Juyoung Yoon","doi":"10.1021/jacs.5c16988","DOIUrl":"https://doi.org/10.1021/jacs.5c16988","url":null,"abstract":"Photoimmunotherapy has been a promising method for eradicating malignant tumors, but remains largely limited by tumor hypoxia and off-target adverse effects. To address these limitations, we develop hypoxia-tolerant small ligand-caged photosensitizer (PS) <b>P1</b>/<b>P2</b> that are delivered to tumor based on an albumin-hijacking strategy by exploiting endogenous serum albumin as a tumor-localized carrier, achieving exceptional tumor accumulation and overcoming tumor hypoxia to realize the combined photoimmunotherapy. Albumin can trigger the acetyl group of <b>P1</b>/<b>P2</b>, initiating a 1,6-rearrangement elimination cascade to release a quinone methide intermediate captured by albumin to form a stable adduct via site-specific 1,6-Michael addition, as verified by in vitro experiments, including high performance liquid chromatography, mass spectra, spectroscopic spectra, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses but control probes <b>P3</b>/<b>P4</b> fail. In vivo imaging revealed that <b>P1</b>/<b>P2</b> displayed more enhanced tumor accumulation post injection than <b>P3</b>/<b>P4</b> did in 4T1-bearing mouse models and <b>P1</b> further enabled broad-spectrum efficacy across several tumor models. Moreover, by light-irradiation-generating superoxide anions and hydroxyl radicals, <b>P1</b>-mediated photodynamic therapy achieves tumor-inhibiting action with approximately 92% regression in a breast mouse model and triggers immunogenic cell death induction, synergizing with programmed death-ligand 1 therapy to further activate systemic antitumor immunity and suppress both primary and distant tumors with approximately 95% tumor growth inhibition. Crucially, this platform may extend its applicability to diverse payloads such as imaging agents, therapeutics, and immunomodulators by replacing the PS warhead and advance delivery methods for clinical imaging and therapy.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"29 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbon buried beneath the surface of a metal catalyst has long been suspected to play a key role in graphene and nanotube synthesis, carbon gasification, carbon fuel cells, and Fischer–Tropsch reactions, but the lack of a technique to detect this carbon unambiguously has stymied its definitive identification in that chemistry. This study reports the first vibrational spectroscopic identification of carbon occupying sites beneath a surface, along with its distinction from surface-adsorbed carbon, by the incident energy dependence of its high-resolution electron energy loss intensity. Its assignment is corroborated by its purposeful synthesis via collision-induced absorption, a technique designed to cleanly synthesize bulk carbon by bombardment of surface-bound carbon with 6 eV Xe atoms that pound it beneath the surface. On a Au–Ni(111) surface alloy, subsurface carbon is found to occupy multiple interstitial sites within the dislocation loop below the alloy surface and in Ni octahedral sites, yielding frequencies of 368, 442 and 509, and 694 cm–1, respectively, consistent with previous density functional calculations. Discovery of the spectroscopic signature of bulk carbon provides a handle for its role and/or its reactivity to be explored and ultimately controlled and optimized over that of surface bound carbon in heterogeneous catalytic reactions and materials properties.
{"title":"Production of Subsurface Carbon by Collision Induced Absorption and Its Vibrational Spectroscopic Identification in Au–Ni(111)","authors":"Santosh K. Singh, Volkan Cinar, S. T. Ceyer","doi":"10.1021/jacs.5c19883","DOIUrl":"https://doi.org/10.1021/jacs.5c19883","url":null,"abstract":"Carbon buried beneath the surface of a metal catalyst has long been suspected to play a key role in graphene and nanotube synthesis, carbon gasification, carbon fuel cells, and Fischer–Tropsch reactions, but the lack of a technique to detect this carbon unambiguously has stymied its definitive identification in that chemistry. This study reports the first vibrational spectroscopic identification of carbon occupying sites beneath a surface, along with its distinction from surface-adsorbed carbon, by the incident energy dependence of its high-resolution electron energy loss intensity. Its assignment is corroborated by its purposeful synthesis via collision-induced absorption, a technique designed to cleanly synthesize bulk carbon by bombardment of surface-bound carbon with 6 eV Xe atoms that pound it beneath the surface. On a Au–Ni(111) surface alloy, subsurface carbon is found to occupy multiple interstitial sites within the dislocation loop below the alloy surface and in Ni octahedral sites, yielding frequencies of 368, 442 and 509, and 694 cm<sup>–1</sup>, respectively, consistent with previous density functional calculations. Discovery of the spectroscopic signature of bulk carbon provides a handle for its role and/or its reactivity to be explored and ultimately controlled and optimized over that of surface bound carbon in heterogeneous catalytic reactions and materials properties.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"89 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dan Ferenc Segedin, Jinkwon Kim, Harrison LaBollita, Nicole K. Taylor, Kyeong-Yoon Baek, Suk Hyun Sung, Ari B. Turkiewicz, Grace A. Pan, Abigail Y. Jiang, Maria Bambrick-Santoyo, Tobias Schwaigert, Casey K. Kim, Anirudh Tenneti, Alexander J. Grutter, Shin Muramoto, Alpha T. N’Diaye, Ismail El Baggari, Donald A. Walko, Charles M. Brooks, Antia S. Botana, Darrell G. Schlom, Hua Zhou, Julia A. Mundy
Layered perovskites─including the Dion–Jacobson, Ruddlesden–Popper, and Aurivillius families─exhibit a wide range of correlated electron phenomena, from high-temperature superconductivity to multiferroicity. Here, we report a new family of layered perovskites realized through topochemical oxidation of Lan+1NinO3n+1+δ (n = 1–4) Ruddlesden–Popper nickelate thin films. Postgrowth ozone annealing induces a substantial c-axis expansion─17.8% for La2NiO4+δ (n = 1)─that monotonically decreases with increasing n. Surface synchrotron X-ray diffraction and coherent Bragg rod analysis (COBRA) reveal that this structural expansion arises from the intercalation of approximately δ ≈ 0.7–1.0 oxygen atoms into interstitial sites within the rock salt spacer layers, far exceeding the previous record of δ ≈ 0.3 for any Ruddlesden–Popper oxide. These oxygen-intercalated phases form a new class of layered perovskites with a spacer layer composition intermediate between the Ruddlesden–Popper and Aurivillius phases. Furthermore, oxygen intercalation induces metallicity, enhances nickel–oxygen hybridization, and suppresses oxygen octahedral rotations, a feature associated with high-temperature superconductivity in Ruddlesden–Popper nickelates. Our work establishes topochemical oxidation as a powerful approach to accessing highly oxidized, metastable phases across a broad range of layered oxide systems, offering new platforms to engineer electronic properties via intercalation chemistry.
{"title":"Topochemical Oxidation of Ruddlesden–Popper Nickelates Reveals Distinct Structural Family: Oxygen-Intercalated Layered Perovskites","authors":"Dan Ferenc Segedin, Jinkwon Kim, Harrison LaBollita, Nicole K. Taylor, Kyeong-Yoon Baek, Suk Hyun Sung, Ari B. Turkiewicz, Grace A. Pan, Abigail Y. Jiang, Maria Bambrick-Santoyo, Tobias Schwaigert, Casey K. Kim, Anirudh Tenneti, Alexander J. Grutter, Shin Muramoto, Alpha T. N’Diaye, Ismail El Baggari, Donald A. Walko, Charles M. Brooks, Antia S. Botana, Darrell G. Schlom, Hua Zhou, Julia A. Mundy","doi":"10.1021/jacs.5c12712","DOIUrl":"https://doi.org/10.1021/jacs.5c12712","url":null,"abstract":"Layered perovskites─including the Dion–Jacobson, Ruddlesden–Popper, and Aurivillius families─exhibit a wide range of correlated electron phenomena, from high-temperature superconductivity to multiferroicity. Here, we report a new family of layered perovskites realized through topochemical oxidation of La<sub><i>n</i>+1</sub>Ni<sub><i>n</i></sub>O<sub>3<i>n</i>+1+δ</sub> (<i>n</i> = 1–4) Ruddlesden–Popper nickelate thin films. Postgrowth ozone annealing induces a substantial <i>c</i>-axis expansion─17.8% for La<sub>2</sub>NiO<sub>4+δ</sub> (<i>n</i> = 1)─that monotonically decreases with increasing <i>n</i>. Surface synchrotron X-ray diffraction and coherent Bragg rod analysis (COBRA) reveal that this structural expansion arises from the intercalation of approximately δ ≈ 0.7–1.0 oxygen atoms into interstitial sites within the rock salt spacer layers, far exceeding the previous record of δ ≈ 0.3 for any Ruddlesden–Popper oxide. These oxygen-intercalated phases form a new class of layered perovskites with a spacer layer composition intermediate between the Ruddlesden–Popper and Aurivillius phases. Furthermore, oxygen intercalation induces metallicity, enhances nickel–oxygen hybridization, and suppresses oxygen octahedral rotations, a feature associated with high-temperature superconductivity in Ruddlesden–Popper nickelates. Our work establishes topochemical oxidation as a powerful approach to accessing highly oxidized, metastable phases across a broad range of layered oxide systems, offering new platforms to engineer electronic properties via intercalation chemistry.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"12 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chiral amides are privileged motifs widely found in pharmaceuticals and natural products, spurring the development of robust synthetic methods. While carbamoyl chlorides are convenient and versatile electrophilic precursors, their application in the stereoselective synthesis of sterically hindered amides, particularly those bearing tetrasubstituted stereocenters, remains a formidable challenge. To address this, we have developed a cobalt-catalyzed asymmetric carbamoyl addition to imines, which enables efficient access to structurally demanding α,α-disubstituted α-amino amides under mild conditions with excellent enantioselectivity. Furthermore, this modular strategy facilitates a one-pot cascade to synthesize enantioenriched 2,5-diketopiperazines (DKPs), important scaffolds in medicinal chemistry. Mechanistic studies reveal stereoselective carbamoyl radical addition to forge the chiral C–C bond.
{"title":"Co-Catalyzed Asymmetric Carbamoyl Radical Addition of Imines","authors":"Wenyu Zhao, Xingyi Shen, Zhaozhao Li, Xuxia Zhang, Aiqi Li, Xianqing Wu, Jingping Qu, Yifeng Chen","doi":"10.1021/jacs.5c22992","DOIUrl":"https://doi.org/10.1021/jacs.5c22992","url":null,"abstract":"Chiral amides are privileged motifs widely found in pharmaceuticals and natural products, spurring the development of robust synthetic methods. While carbamoyl chlorides are convenient and versatile electrophilic precursors, their application in the stereoselective synthesis of sterically hindered amides, particularly those bearing tetrasubstituted stereocenters, remains a formidable challenge. To address this, we have developed a cobalt-catalyzed asymmetric carbamoyl addition to imines, which enables efficient access to structurally demanding α,α-disubstituted α-amino amides under mild conditions with excellent enantioselectivity. Furthermore, this modular strategy facilitates a one-pot cascade to synthesize enantioenriched 2,5-diketopiperazines (DKPs), important scaffolds in medicinal chemistry. Mechanistic studies reveal stereoselective carbamoyl radical addition to forge the chiral C–C bond.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"9 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Evgeniia Ikonnikova, Jung Cho, Xiaodong Zou, Andre Sutrisno, Allen W Burton, Trong Pham, Tom Willhammar
The structural diversity of zeolites depends strongly on the use of organic structure-directing agents (OSDAs) that guide their formation. Low-dimensional zeolitic materials, such as layered or chain-like phases, can serve as key intermediates in topotactic condensation pathways, yet the mechanisms governing their formation and transformation remain poorly understood. Here, we report three low-dimensional zeolitic materials, EMM-75P, EM-L01, and EM-L02, synthesized using benzimidazolium cations as OSDAs. Their structures were determined by three-dimensional electron diffraction (3D ED), including the atomic structure of the OSDAs, revealing their confinement within the framework to shed light on their structure-directing role. The bulky benzimidazolium OSDAs prevent the formation of materials with three-dimensional framework structures and instead direct the formation of low-dimensional zeotypes. Upon calcination, the two-dimensional layered aluminosilicate zeotype EMM-75P undergoes topotactic condensation to form a three-dimensional zeolite, EMM-75, with a previously unreported zeolite framework topology. Aluminosilicate EM-L01 is a 2D analogue of STF/SFF zeolite frameworks and partially condensed to an STF-topology upon calcination, whereas EM-L02, a 1D silicate composed of double 6-ring chains, packed analogous to the CHA zeolite framework, collapses during the thermal treatment. The detailed structural characterization of these three materials provides insights into the mechanism of topotactic condensation and demonstrates how such pathways can lead to new zeolite materials.
{"title":"Low-Dimensional Zeotypes Templated by Stacked Cyclic Benzimidazolium Revealed by Electron Crystallography.","authors":"Evgeniia Ikonnikova, Jung Cho, Xiaodong Zou, Andre Sutrisno, Allen W Burton, Trong Pham, Tom Willhammar","doi":"10.1021/jacs.5c22569","DOIUrl":"https://doi.org/10.1021/jacs.5c22569","url":null,"abstract":"<p><p>The structural diversity of zeolites depends strongly on the use of organic structure-directing agents (OSDAs) that guide their formation. Low-dimensional zeolitic materials, such as layered or chain-like phases, can serve as key intermediates in topotactic condensation pathways, yet the mechanisms governing their formation and transformation remain poorly understood. Here, we report three low-dimensional zeolitic materials, EMM-75P, EM-L01, and EM-L02, synthesized using benzimidazolium cations as OSDAs. Their structures were determined by three-dimensional electron diffraction (3D ED), including the atomic structure of the OSDAs, revealing their confinement within the framework to shed light on their structure-directing role. The bulky benzimidazolium OSDAs prevent the formation of materials with three-dimensional framework structures and instead direct the formation of low-dimensional zeotypes. Upon calcination, the two-dimensional layered aluminosilicate zeotype EMM-75P undergoes topotactic condensation to form a three-dimensional zeolite, EMM-75, with a previously unreported zeolite framework topology. Aluminosilicate EM-L01 is a 2D analogue of <b>STF</b>/<b>SFF</b> zeolite frameworks and partially condensed to an <b>STF</b>-topology upon calcination, whereas EM-L02, a 1D silicate composed of double 6-ring chains, packed analogous to the <b>CHA</b> zeolite framework, collapses during the thermal treatment. The detailed structural characterization of these three materials provides insights into the mechanism of topotactic condensation and demonstrates how such pathways can lead to new zeolite materials.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":" ","pages":""},"PeriodicalIF":15.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146123259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We show the dynamic covalent exchange between merocyanines and imines and demonstrate how the equilibrium composition can be shifted with visible light. For this purpose, we exploited a negative photochromic T-type merocyanine that engages in a covalent exchange with an aniline nucleophile to provide an imine. Since the merocyanine can quantitatively be converted into its spiropyran isomer that is nonreactive in the exchange, the system can be shifted and trapped in the static spiropyran state. In the dark, however, the system thermally reverts back to the dynamic merocyanine that re-engages in the exchange. The process of shifting/trapping and re-equilibration can be repeated multiple times. The system provides opportunities for designing materials that allow for spatial and temporal control over their dynamic properties.
{"title":"Shifting Merocyanine-Imine Exchange with Visible Light","authors":"Alwin Drichel, Stefan Hecht","doi":"10.1021/jacs.5c17606","DOIUrl":"https://doi.org/10.1021/jacs.5c17606","url":null,"abstract":"We show the dynamic covalent exchange between merocyanines and imines and demonstrate how the equilibrium composition can be shifted with visible light. For this purpose, we exploited a negative photochromic T-type merocyanine that engages in a covalent exchange with an aniline nucleophile to provide an imine. Since the merocyanine can quantitatively be converted into its spiropyran isomer that is nonreactive in the exchange, the system can be shifted and trapped in the static spiropyran state. In the dark, however, the system thermally reverts back to the dynamic merocyanine that re-engages in the exchange. The process of shifting/trapping and re-equilibration can be repeated multiple times. The system provides opportunities for designing materials that allow for spatial and temporal control over their dynamic properties.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"89 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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